Tractor-trailer braking systems and operating mechanism



Feb. 22, 1966 H. GREENTREE 25,968

TRACTOR-TRAILER BRAKING SYSTEMS AND OPERATING MECHANISM 4 Sheets-Sheet 1Original Filed Jan. 17, 1963 INVENTOR Herbert Greenrree ATTORNEYS Feb.22, 1966 GREENTREE Re. 25,968

TRACTOR-TRAILER BRAKING SYSTEMS AND OPERATING MECHANISM 4 Sheets-Sheet 2Original Filed Jan. 17, 1963 llllllllln INVENTOR Herbert Green/rec BYW%4{ 7% ATTORNEYJ Feb. 22, 1966 GREENTREE Re. 25,968

TRACTOR-TRAILER BRAKING SYSTEMS AND OPERATING MECHANISM 4 Sheets-Sheet 5Original Filed Jan. 17, 1963 m vw o9 w m n N J w M 4 O m N 6 mm; 0+ N nL r l e 0 mm mm m r 0 ON\ 00 Q a F H no. wor o N: n:

Om m: m m 0: mm Ow. m:

ATTORNEYS Feb. 22, 1966 H. GREENTREE TRACTOR-TRAILER BRAKING SYSTEMS ANDOPERATING MECHANISM 4 Sheets-Sheet 4 Original Filed Jan. 1'7, 1963 HQMN. m: 4 mt Q1 T mt r! H m9 4 j m 3 mt m2 @9 5 INVENTOR Herbert Greenfree BY f zwr Zz ATTORNEYS mm mm.

United States Patent 0 25 968 TRACTOR-TRAILER BRAKING SYSTEMS ANDOPERATING MECHANISM Herbert Greentree, Lake Worth, Fla., assignor ofone-half to Geraldine I-I. Greentree, Lake Worth, Fla.

Original No. 3,135,358, dated June 2, 1964, Ser. No.

252,078, Jan. 17, 1963. Application for reissue Apr.

26, 1965, Ser. No. 456,601

28 Claims. (Cl. 1883) Matter enclosed in heavy brackets I: appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

The present invention relates to a braking system for tractor-trailervehicles and more particularly to control means for applying the trailerbrakes in proper sequence relative to the application of the tractorbrakes.

The systems in use are of two general types, one being a purelyhydraulic system and the other being a combination of hydraulic andelectric systems wherein the hydraulic system is applied to the tractorwhile the electric system is used on the trailer. In each of thesesystems the trailer braking system is so intimately associated with thetractor braking system that a failure of the tractor braking system alsoresults in a failure of the trailer braking systems.

[One example of a hydraulic electric system is that which is illustratedand described in United States Patent No. 2,260,641 to F. M. Reid,issued October 28, 1941. The tractor system comprises a master cylinderhaving a spring biased piston for creating a braking pressure through apiping system leading to a braking cylinder at each tractor wheel.Pistons in the wheel cylinders, likewise biased by springs, applypressure against the brake shoes to decelerate the vehicle. The pipingsystem usually includes hose connections between the piping system andtwo or more wheel cylinders that are subject to deterioration andbreakage rendering the system ineffective] [The electric brake system isconnected to the hydraulic system as by the connection of a controllerto the same piping system. This controller includes a plunger, springbiased in one direction and pressure operated in the opposite direction.The plunger actuates a means for connecting the electric brake system toa source of electric current through a high resistance and forsuccessively shorting out portions of the resistance as the brakepressure is increased] [As will be seen, failure of the pressure in thehydraulic system also results in a failure of the electric brakes. Alsothe proper sequence of operation of the two brake systems is hard tosecure and maintain] [Systems designed to overcome the dependency of theelectric brake system on the good working order of the hydraulic brakesystem have resulted in a separate and independent means, usually handoperated, being provided and located on or near the steering post. Incase of failure of the hydraulic system on the tractor, the handoperated means may be operated to apply the trailer brakes. However,this poses a problem of operating two hand brakes at the same time andsimultaneously steering the vehicle. The maximum amount of safety cannotbe attained by a system of this kind. An example of this system is shownin United States Patent No. 2,454,- 291 to W. F. Penrose, issuedNovember 23, 1948.]

A primary object of this invention is to overcome the many disadvantagesof the prior art structures to provide a system that is safe anddependable.

Another object of this invention is the provision of a tractor-trailerbrake system wherein the two systems are independent of the operabilityof each other.

"ice

Another object of this invention is to provide a trailer brake systemthat may easily and simply be associated with the tractor or car brakingsystem without modification of the tractor brake system.

A further object is to provide a combined tractor and trailer brakeactuating and synchronizing unit which is adapted for convenientmounting on and connecll'on with the conventional actuating linkage forthe brakes of an automotive vehicle.

Still another object of the present invention is to provide atractor-trailer brake system that may easily be adjusted for propersequence of application of brakes and easily maintained in properadjustment.

Other objects of the invention, its various advantages, and meritoriousfeatures will more fully appear from the following description, appendedclaims, and the accompanying drawings, wherein:

FIGURE 1 is a side elevational view of a tractor-trailer assemblywherein the tractor is an automobile and the invention is appliedthereto;

FIGURE 2 is an elevational diagrammatic view, partly in section of oneembodiment of the invention;

FIGURE 3 is a diagrammatic elevational view partly in section disclosingthe application of the control element of the FIGURE 1 embodiment to thebrake pedal;

FIGURE 4 is a sectional view through the pedal supported plate assemblyand contactor mechanism of another embodiment of the invention;

FIGURE 5 is a sectional view on lines 55 of FIG- URE 4 with the remotelylocated controller box shown connected to the contractor mechanism;

FIGURE 6 is a sectional view through a further embodiment of theinvention; and

FIGURE 7 is a sectional view on line 7--7 of FIG- URE 6.

Referring to FIGURES 1 to 3, an automobile-trailer combination asillustrated, represents one form of tractortrailer combination to whichthe invention is applicable. The automobile 1 is provided with its ownconventional hydraulic brake system 2 having a foot pedal 4 for theactuation of the brakes through the medium of the hydraulic system. Sucha system comprises a master cylinder 3 connected to the separate wheelcylinders by piping means with the brake pedal 4 connected to a piston(not shown) in the master cylinder. The trailer 5 is provided with anelectrical brake system 6 having an electromagnet (not shown) at each ofthe trailer wheels W for applying the brakes thereto. The electricalbrakes per se are conventional and form only an element of the system ofwhich the present invention is concerned. Any type of electrical brakemay be used on the trailer 5 and any type of brake system may be used onthe automobile or tractor 1 so long as it includes a foot pedal actuator4. The preferred mode of operation of the combined braking system is tohave the trailer brakes applied slightly in advance of the applicationof the tractor brakes and in a manner such that greater brakeapplication is simultaneously applied to the trailer after the tractorbrakes are increasingly applied. It is also desirable to provide asystem in which the trailer brakes can be independently applied, and onewhich is not dependent on the good working order of the tractor brakes.

The form of the invention disclosed in FIGURE 2 provides a hydraulicpulsator type trailer brake control system having a pair of expandibiebulbs or chambers 7 and 8 connected by non-expandible tubing 9. Whilebulbs 7 and 8 are disclosed, it is to be understood other types ofexpandible chamber devices may be used in lieu thereof in the pulsatortype system. The system is so arranged that when one of the bulbs issqueezed or flattened, the other bulb is expanded as it receives theliquid discharged from the first bulb. The expansion of the second bulbis restrained in all directions except one where it operates against amovable partition of the chamber that encloses the second bulb.

The system includes bulb 7 mounted upon the foot tread of the brakepedal 4 of the tractor or car drawing the trailer. Any type of means forpositioning and maintaining the bulb on the brake pedal may be used. Theexample herein disclosed, includes arched base plate of metal thattightly embraces the brake pedal 4 and serves to hold bulb 7 on thebrake pedal tread plate. Bulb 7 rests against plate 10 and is heldthereto by a metal plate 11 hingedly riveted or otherwise fixed at 12along one of its edges to plate 10. Bulb is made of a material that isreadily deformed by pressure applied to its surface, for example, vinylplastic. The bulb is connected by relatively non-expandible tubing 9 toa similar bulb 8, housed in a walled chamber 14 provided with a movablepartition wall 16. Chamber 14 is mounted on the dash or on the steeringpost of the tractor or car with a handle-like extension 15 of partitionwall 16 extending through a wall thereof for a purpose to be presentlypointed out.

As pressure is applied to bulb 7 the fluid in this bulb is forced outalong tubing 9 into bulb 8 to apply a force to or against the movablewall 16, causing it to be moved counterclockwise outwardly as viewed inFIGURE 2 around its pivot connection 17. The amount of movement of wall16 is in direct proportion to the deformation of bulb 8.

To fill and to replenish liquid within the pulsator system, there may beprovided a reservoir 18 having a filling opening 19 at the top and aconnection at its lower end in communication with the bulb 8. Theconnection 20 preferably employs a cut-off valve 22 to pre vent fluidreturning to the reservoir once the system is fully charged.

The movable wall 16 and its extension 15 provides the trailer brakecontroller and forms a means for hand manipulation of the trailerelectric brakes as will presently appear. Wall 16 is biased by springmeans 34 attached at one end to ear 36 affixed to wall 16 and at theother end to a second lever 38 pivoted at 40 to stationary wall 41 ofchamber 14. Lever 38 has a threaded nut 42 horizontally pivotallymounted therein intermediate the ends of the lever. Nut 42 is engaged byscrew 44 extending through wall 41 with its knurled head 46 abutting theouter face of wall 41. Rotation of screw 44 in one direction draws wall16 toward wall 41 to increase the tension of. spring 34 and take up anylost motion in the bulb operating system and to force movable wall 16against bulb 8. Rotation of screw 44 in the opposite direction releasessome of the tension on the spring thereby adjusting the amount ofpressure required to expand bulb 8 and cause movement of wall 16.

Wall 16 also carries an insulating pad 48 for slidingly engaging the endof a spring contact fixed at its other end to a post 49 supported inwalled chamber 14. As wall 16 is moved in a clockwise direction byexpansion of bulb 8, pad 48 pushes against the end of the spring contact50 to deform it and cause it to come into successive engagement with aplurality of spaced contacts 52-56 fixedly mounted in walled chamber 14.Contacts 52-56 connect with resistors 57-61, each contact connectingwith a separate resistor of different resistance. Spring contact 50 isconnected through post 49, a lead 62 including the conventional magnets(not shown) of the trailer brake system 6 to one terminal of a supply ofelectric current 64, such as a battery. The circuit through therespective resistors 57-61 are all connected to a single buss 63 whichin turn is connected to the other terminal, preferably the powerterminal of battery 64, completing the electric circuit between thecontroller, source of electric current and the electro-magnetic brakes.

When pressure is applied to movable plate 11 on the face of the brakepedal 4, bulb 7 is first depressed, forcing fluid from it through thetubing 9 and into bulb 8. There the fluid exerts a pressure on movablewall 16 to cause wall 16 to be pivoted clockwise against the bias ofspring 34 thereby deforming spring contact 50 successively intoengagement with contacts 52-56. This causes current to flow in the brakecircuit first with an initially low current intensity to partially applythe trailer brakes and then as spring contact 50 engages successivecontacts to increase the current intensity and application of thebrakes. Continued pressure on plate 11 moves brake pedal 4 tosimultaneously begin application of the tractor or car brakes to halt orretard the forward motion of the assembly.

The amount of application of the trailer brakes relative to the tractorbrakes can be adjusted by turning screw 44, one direction of rotationincreasing the tension of spring 34 and the resistance to movement ofwall 16 in turn causes the brake pedal to move to apply the tractorbrakes as pressure is applied to it. Decreasing the tension of spring 34results in an opposite effect, it decreases the resistance that thelever 24 exerts against wall 16 and as a consequence pressure on thebrake pedal causes an initially greater application of theelectro-magnetic brakes prior to application of the tractor or carbrakes. This is obvious from the fact that pressure applied to the brakepedal is through the medium of the bulb 7. Should it yield underpressure the brake pedal will not move or will move to a lesser extentbecause of the yielding of the bulb 7.

If desired, means may be provided to inject fluid under pressure intobulb 7 to take up lost motion between plate 11 of the brake pedal andwall 16. Injecting fluid into the system expands both bulbs against theelements of the chambers that confine them, assuring that pressure isimmediately applied through the tubing when pressure is applied to thebrake pedal. This adjustment also pro vides for correction of the fluidpressure under changes of temperature.

As can be seen from FIGURE 2 handle-like extension 15 may be operated byhand by grasping the protruding knobbed end and moving it against thetension of spring 34. Releasing the lever releases the brakes as thespring 34 returns it to its normal off position.

This embodiment provides an easily installed, simply adjusted trailerbrake controller and one that is independent of the workable conditionof the tractor brake system, and one that assures great safety.

In the embodiment of FIGURES 4 and 5, an electrical system is used toobtain the same desired mode of operation and safety features of thepreceding embodiment. Instead of the fluid link between the brake pedaland spring contact 50 the embodiment of FIGURES 4 and 5 provides anelectrical link. There are two contactors, one in the casing 70 mountedon the steering post or dash of the tractor or car designed for handmanipulation and the other mounted on the foot pedal 4 designed for footmanipulation. The contactors are connected to the same set of resistorsand either of the contactors may be independently and selectivelyoperated.

Casing 70 containing the hand operated contactor and the resistors forthe electric brake circuit may be mounted on the steering post or otherpart of the vehicle near the driver. It pivotally mounts hand contactorlever 72. Lever 72 extends through slot 74 in the casing and the outerend has a knob 76 affixed thereto to be readily grasped by the hand. Atension spring 78 has one end connected to casing 70 and the other endconnected to lever 72 for normally biasing the lever towards its offposition disrupting the braking circuit as will presently appear.

Positioned adjacent to lever 72 and arranged for successive engagementby lever 72 is a plurality of knife type contacts 80-84. These contactsare mounted on an insulating member fixed to casing 70. The individualcontacts may be affixed to the insulating member 95 by rivets or screwsforming points or terminals for connection thereto of the respectiveelectrical leads.

The space behind insulating member 90 is used to house a plurality ofresistors indicated generally by numeral 91, each connected at one endto a common buss 92 and at their other ends to individual contacts. Theresistors preferably provide different resistances as desired. Theconnections and contacts are arranged such that the first contact to beengaged by lever 72 completes the brake circuit through a highresistance resistor 93 and the source of electric current 64. As eachcontact is successively engaged by lever 72 each of successive resistor94 through 97 is connected in parallel to reduce the total resistance ofthe brake circuit and to increase the current flow through the brakemeans until it becomes a maximum for maximum application of the brakes.

Lever 72 is connected by conductor 98 to the brake means and buss 92 isconnected to one terminal of the source of electric current 64 the otherterminal of which is connected by conductor 100 to the brake means thuscompleting the brake circuit.

For foot operation of the electric brakes there is a plate meansprovided on the brake pedal 4 for engagement by the foot and throughwhich motion of the brake pedal is compelled. The pressure applied tothis plate means is arranged to connect the resistors in the brakecircuit successively as the braking pressure is increased.

The plate means comprises base plate 104 fastened to the brake pedal asby through bolts 106. One edge of the base plate is provided with agroove 108 which fixedly receives one edge of an upper flexure plate110. Upper plate 110 is biased in an upward direction by spring means112, here illustrated as a semi-elliptical leaf spring riveted at 113 tobase plate 104 with its ends extending upwardly into abutting engagementwith the underside of upper plate 110. Upward movement of plate 110 islimited by an adjustable stop means that permits plate 110 to be moveddownward when pressure is applied thereto.

The stop means comprises an inverted cylinder 114 attached to base plate104 as by rivets (not shown). The upper end of cylinder 114 is inwardlyflanged to reciprocally receive a second outwardly flanged cylinder 116.The cylinders slide within one another with their respective flangescooperating to prevent relative rotation and axial separation. Cylinder116 is provided with a centered threaded aperture to receive in threadedengagement adjustment screw 118 passing through an aperture in the upperplate and formed with a head 119 adapted to abut the aperture definingportion of plate 110 as plate 110 is biased upwardly and the cooperatingflanges of the reciprocable cylinders engage. By adjusting screw 118inwardly and outwardly of cylinder 116 the clearance between plates 104and 110 and the tension of spring 112 may be adjusted.

The amount the plate 110 moves prior to movement of brake pedal 4depends on the relative strengths of the springs resisting theirmovement. Adjustable stop means 114-119 provides a means for adjustingthe tension of spring 112 relative to the tension of the springresisting the movement of brake pedal 4. For example, as screw 118 isturned to pull upper plate 110 downwardly, there will be a compressionof spring 112 increasing its initial resistance to movement toward plate104. Rotation of screw 118 in the opposite direction lowers the tensionof spring 118 permitting plate 110 to be moved more readily relative toplate 104.

Relative movement of plates 104 and 110 is effective to cause successivecontact of spring contact 50 with contactors 126430 connected inparallel to knife contacts 80 to 84 through an adjustable cam means 120provided to compensate for adjustment of the compression of spring 112.Cam means 120 is mounted on the under side of upper plate 110 andcomprises a three-armed lever 121 pivotally mounted on the underside ofplate 110. All

arms are integral with a hub and move about their pivot as a unit. Onearm 122 has its one outer end bifurcated to embrace screw 118 and restatop cylinder 116, while its other end extends toward upper plate andoverlies a biasing spring 123 (FIGURE 5) operative to yieldinglymaintain arm 122 in abutting contact with cylinder 116 during alloperative adjustment of the tension in spring 112. The second arm 124extends substantially at right angles to arm 122 and engages aninsulating pad 125 (FIGURE 5) on spring contact 50. Contact 50 overliescont-actors 126-130 attached through insulating blocks 136 to base plate104. Motion downwardly of upper plate 110 is transferred through cam arm124 to deform spring contact 50 and cause it to successively engagecontacts 126-130 respectively connected by the multiple leads in cable138 to resistors 9397 in casing 70.

Cam means 120 normally moves with plate 110 as a fixed linkage betweenplate 110 and spring contact 50. When the adjustable stop means isactuated to correct for the maladjustment of the two brake systems,lever 121 is moved around its pivot to move its integral arm 124 towardor away from contact 50, etfecting a shortening or lengthening of thelinkage between plate 110 and contact 50 as plates 104 and 110 are movedcloser together or further apart.

The pressure applied to upper plate 110 compresses spring 112 andoperates cam means 120 to deform spring contact 50 successively engagingthe contacts 126-130 and progressively applying the trailer brakes. Thisincreasing pressure on the brake pedal simultaneously causes the brakepedal to move and apply the tractor or car brakes in the same manner asin the previous embodiment of the invention.

A third embodiment of the invention is disclosed in FIGURES 6 and 7. Inthis embodiment the means for operating the controller to jointly applythe brakes on the tractor and trailer and means for independently controlling the trailer brakes is incorporated in a single structuremounted on the brake pedal requiring only an aflixing of the means tothe brake pedal and a connection of two wires, one to the source ofelectric current and the other to the trailer brakes.

This embodiment provides a base plate 140 attached to the brake pedal bystuds 142 and formed to provide a piano type hinge pivot 144 for anupper plate 146 and a well 148 housing the controller elements.

Upper plate 146 hinged at 144 extends over the brake pedal and overlieswell 148 providing a movable cover for the controller. Downward motionof upper plate 146 is resisted by a plate-like leaf spring 150 rivetedat 152 to base plate 140. A laterally adjustable camming means 154 isdisposed between the upturned free end of spring 150 and the under sideof upper plate 146. Camming means 154 is in the form of a metal blockmounted on the outer end of one arm 156 of a bell crank lever 158 theother arm 159 of which extends beyond one side boundary of plate 146 tobe grasped and moved for ad justing the tension of the spring 150. Bellcrank lever 158 is mounted for pivotal movement on a pivot pin 160 fixedto plate 146.

As best shown in FIGURE 7, the free end of spring 150 is bent into aplane substantially at right angles to the main body of the spring andis inclined to provide a carnming surface 161 with which block 1.54engages. As bell crank lever 158 is rotated, clockwise around its pivotas viewed in FIGURE 7, the block rides upwardly along camruing surface161 of spring 150 to increase the initial tension of spring 150. Motionof hell crank 150 in the opposite direction results in a decrease in theinitial tension of spring 150. By this adjustment the relative degree ofbraking as between the tractor and trailer brake systems may be effectedas previously pointed out.

Upward relative movement of upper plate 146 is limited by a screw 162threaded into the well housing and passing through a slotted bar 164depending from the under side of the plate 146. Stop screws 166 are alsoprovided for limiting the downward motion of the plate 146.

The controller switch consists of a plurality of knife contacts 167-171mounted in spaced relation along an insulating strip 176 fixed to a sideWall 178 of well 148 by screws 179. Beside the switch and in well 148,there is mounted a plurality of resistors 172. 173, 174 and 175 havingone terminal of each connected to a buss 182 and the other terminalconnected to the respective contacts. Contact 171 is directly connectedto buss 182 by lead 183. A knife blade contact 184 of hell crank shapeis pivoted at the free end of one arm to one of screws 185 threaded intoinsulating strip 176 and securing a U-shaped journal and contact supportbracket B thereto. The other arm of blade contact 184 overlies theplurality of contacts 167171 and is adapted upon downward movement tosuccessively engage the contacts. Blade contact 184 is biased toward itsupper disconnect position by compression spring means 186 (FIGURE 7)acting between the under edge of blade contact 184 and abutting at itsother end the top edge of bracket B. Screw 185 serving as the pivot forblade contact 184 is directly connected to one terminal of the source ofelectrical energy by lead 187.

On the underside of the plate 146 overlying blade contact 184 there is aspring-like actuator member 188. Member 188 is clamped at one end toplate 146 as shown by clamp plate and screw assembly 189 (FIGURE 6) andextends beyond the other side of the plate 146 to form a hand holdwhereby it may be deflected downwardly relative to plate 146. Theunderside of the member 188 carries a strip of insulation 190 (FIGURE 7)against which the upper end of the blade contact 184 engages when levermember 188 is manually depressed to force blade contact 184 into contactwith the contacts 167-171. The resilient character of member 188 permitsthe blade contact 184 to be actuated independently of applying pressureto the brake pedal and thus permits the testing of the trailer brakesand the application of the trailer brakes independently of the tractorbrakes 14 when desired.

The buss 182 is connected by lead 191 to the other terminal of thesource of electric current through the electromagnetic brakes as in thepreviously described embodiments.

As in the previously described embodiments of the invention pressureapplied to the brake pedal through the mechanism mounted thereon firstapplies the trailer brakes and then simultaneously applies both thetrailer and tractor brakes. Successive engagement of the contacts 167-171 by blade contact 184 is effective to cause the current to increasein the electromagnetic means that actuates the trailer brakes.

It will be apparent from the foregoing that the desired synchronizedapplication of the brakes of a tractor-trailer t'chicle is achievedthrough an auxiliary pedal member such as the curved plate 146 in FIG. 6adapted to be connected yieldably to the conventional brake actuatinglinkage of a tractor so that, when foot pressure is applied to theauxiliary pedal in the natural manner, the latter moves relative to itssupport 140 and the supporting brake pedal 4 and against the adjustedforce of the spring 150 to move the actuating element 184 of the trailerbrake controlling rhcos'mt. At the some time, this foot pressure istransmitted to the conventional linkage to actuate the tractor brakes inpropcr synchronism with the trailer brakes as rlctermined by the manualadjustment of the motion transmitting connection bcrn'ccn the plate andthe tractor brake linkage. By hinging the plate 146 onto a supportattachable to a part of the conventional tractor brake linkage such asthe pedal 4 on which at least the contact mecha nism of the electricbmkc controller are mounted, the entire independently operable electrictrailer brake actuator and synchronizing structure may be combined in aunifury structure which may be attached conveniently to a part, such asthe pedal 140, of the conventional actuating linkage of a modernautomotive tractor vehicle. Location of the hinge 144 at one end of theconvexly curved plate 146 and spacing the latter adjacent and above thesupport I 50 facilitates the natural application of the actuating footpressure in a direction not only to actuate the trailer brukc controllerbut also the conventional pedal for the tractor brakes.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. A control system for trailer wheel brakes of a tractortrailerassembly wherein the tractor and trailer have independent brakingsystems comprising a brake pedal and a first source of brake power onsaid tract-or for applying said tractor brakes,

a second source of brake power independent from said first source ofbrake power for applying said trailer brakes,

controller means intermediately connected between the second source ofbrake power and the trailer brakes for pre-actuating said trailer brakesand normally regulating the power applied to the trailer brakes toassure predetermined controlled actuation of said trailer and tractorbrakes,

means responsive to foot pressure applied to actuate the brake pedal foractuating said controller comprising yieldable means mounted on saidbrake pedal for motion relative thereto, and

motion transmitting means connecting said yieldable means to saidcontroller.

2. The control system of claim 1 wherein said motion transmitting meanscomprises a collapsible fluid chamber means forming a part of andcollapsible by said yieldable means,

an expandible fluid chamber means at said controller, connected to movein response to collapse of said collapsible chamber means and anon-expansible, non-compressible fluid link between said chamber means.

3. The control system of claim 1 wherein said means for actuating saidcontroller comprises yieldable means mounted on said brake pedal formotion relative thereto, and

mechanical means connected with said yieldable means and movabletherewith engaging said controller for moving said controller to applythe trailer brakes.

4. The control system of claim 1 wherein said means for actuating saidcontroller includes operable means efi'ective irrespective of theoperativeness of said tractor brakes.

5. The control system of claim 1 wherein said controller is mounted on atractor part adjacent the driver and includes means for actuating saidcontroller independently of said first mentioned means for actuatingsaid controller.

6. The control system of claim 1 wherein said controller is mounted onand carried by said brake pedal and includes means for actuating saidcontroller independently of said first mentioned means for actuatingsaid controller.

7. A control system for electromagnetic trailer brakes of a tractortrailer assembly having independent wheel brakes for the tractor vehiclecomprising a brake pedal and a first source of brake power operativelyconnected to a first actuator for the tractor brakes;

a second source of brake power having an electrical contactor includinga series of stationary resistors of varying resistance having contactsarranged in a path for successive engagement by a movable contactor,

a movable contactor, and

actuator means independent of said first actuator fixed to said footpedal and normally biased to a nonactuating position for actuating saidmovable contactor, said actuator means being movable toward its fullbraking position in accord with foot pressure applied by the operator tosaid foot pedal.

8. The control system of claim wherein said actuator means is biased toits non-actuating position spaced from the foot engaged portion of saidfoot pedal actuator by a biasing means having an increasing resistanceto relative movement of said actuator means and said brake pedal as saidactuator means approaches full braking position whereby the trailerbrakes are initially engaged upon normal braking action of the driverprior to application of said tractor brakes and thereafter are appliedwith continuing greater force as the brake pedal actuator applies saidtractor wheel brakes.

9. The control system of claim 5 wherein said actuator means includesmeans operative to apply said trailer brakes fully in event of failureof said tractor brakes.

10. A control system for the tractor and trailer brakes of atractor-trailer assembly, said tractor and trailer having independentbrake systems: a brake pedal and a source of brake power for applyingsaid tractor brakes, a source of electric power for applying saidtrailer brakes, and a controller and circuits connecting said controllerto said source of electric power and to said trailer brakes including;

(a) a plurality of resistors,

(b) hand operable lever means to actuate said contactor means, and

(c) actuator means for actuating said hand operable means by means offoot pressure on said brake pedal during the application of the tractorbrakes comprising:

(1) a flexible fluid bulb mounted on said brake pedal through whichpressure is to be applied to said brake pedal,

(2) a second flexible fluid bulb operably associated with said handoperable lever, and

(3) tubing means connecting said flexible bulbs whereby pressure appliedto said brake pedal will cause the fluid in said first bulb to flow tosaid second bulb and expend it against said hand operable lever to applysaid trailer brakes.

11. A control system for the tractor and trailer brakes of atractor-trailer assembly, said tractor and trailer having independentbrake systems: a brake pedal for applying said tractor brakes, a sourceof electric power for applying said trailer brakes, and a controller forapplying said electric power to said trailer brakes comprising;

(a) a plurality of resistors of increasing resistance arranged to beconnected in parallel to apply said electric power in graduated steps tosaid trailer brakes, and

(b) a hand operable means for successively connecting said resistors inparallel to apply said electric power,

foot actuated means for successively connecting said resistors inparallel to apply said electric brakes comprising;

(a) a yieldable member mounted on the foot engaged portion of said brakepedal,

(b) spring means biasing said yieldable member to an inoperativeposition,

(c) means for adjusting the compression of said spring means,

(d) contactor means, and

(e) linkage means between said yieldable means and said contactor,whereby said contactor means is oper- In spring,

and means responsive to the adjustment of said means for limiting theupward movement of said yieldable means for compensating for a change ofrange of movement effected by said adjustment by altering the effectivelength of said linkage means and the mechanical advantage thereof. 13. Acontrol system for the tractor and trailer brakes of a tractor-trailerassembly said tractor and said trailer having independent brakingsystems: a brake pedal and a source of power for applying the tractorbrakes, a source of electric power for applying the trailer brakes, andmeans mounted on said brake pedal for controlling the application ofsaid electric power to said trailer brakes when said tractor brakes arebeing applied comprising;

(a) a plurality of resistors of increasing resistance,

(b) a circuit including said source of electric power connecting saidresistors in parallel to said trailer brakes,

(c) manually operable contactor means responsive to foot pressureapplied to actuate the brake pedal for successively connecting saidresistors in said circuit,

(d) yieldable means mounted on said brake pedal and movable relativethereto (e) means for resisting the movement of said yieldable means inproportion to the extent of relative motion thereof,

(f) means for adjusting said means for resisting movement to regulatethe movement of the yieldable means relative to the movement of thebrake pedal, and

(g) contactor means actuated by said yieldable means for successivelyconnecting said resistors in parallel and effecting gradual applicationof electric power to said trailer brakes.

14. The control system as set forth in claim 11 wherein the means foradjusting the means resisting the movement of the yieldable meanscomprises a leaf spring fixed at one end,

a cam surface on the other end of said spring, and

block means between said yieldable means and said cam surface adjustablymovable along said cam surface for flexing said spring relative to saidyieldable means to adjust the resisting force exerted thereby.

15. A controller for the trailer brakes of a tractortrailer assemblyhaving electromagnetic trailer brakes responsive to a source ofelectrical energy and foot pedal actuated tractor brakes responsive toan independent source of brake power comprising a series of resistorsconnected in parallel in a circuit adapted for insertion in a circuitincluding said electromagnetic brakes and said source of electricalenergy,

contactor means for successively energizing said series of resistors toprogressively increase the electrical energy supplied to saidelectromagnetic brakes and means responsive to the foot pressure appliedto said foot pedal for initially actuating said contactor means to applysaid trailer brakes and thereafter progressively and simultaneouslyincreasing the application of said trailer brakes as said tractor brakesare applied.

16. The controller of claim 15 wherein said means responsive to the footpressure applied to said foot pedal 75 comprises:

a plate assembly including a mounting plate adapted for attachment tothe tread of the foot pedal and an actuator plate hingedly connected tosaid mounting plate,

adjustable means biasing said actuator plate away from said mountingplate whereby the initial actuating foot pressure may be varied torelate the sequence of operation of the tractor and trailer brakes toassure application of the trailer brakes ahead of the tractor brakes andthereafter greater application of the trailer brakes until maximumapplication of the tractor and trailer brakes occurs.

17. The controller of claim 16 wherein said adjustable means comprisesan expansible and compressible fluid bulb.

18. The controller of claim 16 wherein said adjustable means comprises:

a biasing spring, and means for selectively tensioning said biasingspring to vary its initial resistance to movement of said actuator platetoward said mounting plate.

19. The controller of claim 18 wherein said series of resistors and saidcontactor means are mounted on said mounting plate.

20. The controller of claim 18 wherein said contactor means is mountedon said mounting plate and electric leads extend from said mountingplate to said series of resistors remotely located with respect to saidbrake pedal.

21. The system of claim 1 wherein said independent braking systemsinclude braking means operable independent of operation of the engine ofsaid tractor.

22. The system of claim 1 wherein said independent braking systemsinclude actuation means which are separately synchronically actuatableat a single position.

23. For use in synchronizing the application of electric brakes on atrailer with the brakes on a tractor vehicle coupled to the trailer andenergized by foot depression and actuation of a conventional brakepedal, the combination of, a first plate adapted to be secured againstthat surface of the brake pedal on which toe pressure is normallyexerted to apply the vehicle brakes, a cover plate spaced above saidfirst plate and hinged on the latter to swing toward and away from theplate about an axis disposed generally parallel said pedal surface, re--silient means acting between said plates and urging the cover plate awayfrom said pedal surface to a normal broke-released position, the stressof the resilient means increasing progressively with the movement ofsaid cover plate toward said first plate, a controller adapted for con--nection with said trailer brakes and actuated by depression of saidcover plate relative to said first plate to mainruin the trailer brakesinactive when said cover plate is in: said released position whileincreasing the energization of such brakes progressively as the coverplate is swung about said axis toward the first plate by pressureapplied by an operators toe in a single position of the operators footrelative to the cover plate whereby the energizations of the tractor andtrailer brakes respectively are determined by the stress in saidresilient means and the swinging of said cover plate relative to saidfirst plate under the applied foot pressure.

24. The combination as defined in claim 23 in which said resilient meansincludes a leaf spring mounted cantilever fashion on one of said platesand engageable along its free edge portion by an abutment mounted on theother plate for engagement with the spring at different points, andselectively operable means to adjust the position of said abutment andthereby vary the effective length of the spring when said cover plate isdepressed.

25. The combination as defined in claim 23 in which said trailer brakecontroller includes contact elements enclosed in a housing formed by theplates.

26. The combination as defined in claim 23 in which said controllerincludes a row of insulated contacts mounted on one of said platesadjacent the free edge of said cover plate and spaced along said hingeaxis, and a single contact mounted on one of said plates and extendingacross said row for engagement with the successive insulated contactsduring the progressive depression of said cover plate.

27. A device as defined in claim 23 in which said controller includescontact elements and in which said plates form a housing enclosing saidresilient means and said Contact elements, and said device includesmeans accessible from the exterior of said housing and adjustableselectively to vary the stress of the resilient means for a givenapplied foot pressure.

28. A device as defined in claim 23 in which said plates form a housingwhich encloses said resilient means and the parts of said controller andwhich may be opened by swinging said plates apart about the hinge axis.

References Cited by the Examiner The following references, cited by theExaminer, are of record in the patented file of this patent or theoriginal patent.

UNITED STATES PATENTS 1,880,958 10/1932 Farmer. 2,045,886 6/1936Tibbetts l88162 X 2,165,320 7/1939 Weiss et al. 303---8 2,452,03310/1948 Born 188-3 X 2,834,434 5/1958 Stuart l883 FOREIGN PATENTS103,981 5/1938 Australia.

DUANE A. REGER, Primary Examiner.

